On page 138 of my edition of The Light Fantastic, Cohen the Barbarian tells Twoflower and Rincewind about trolls, and tries to say a word that I cannot at all identify (emphasis added):

"Trollsh never ate anybody."

"No?"

"No, they alwaysh spit the bitsh out. Can't digesht people, see? Your average troll don't want any more out of life than a nice lump of granite, maybe, with perhapsh a nice slab of limeshtone for aftersh. I heard someone shay it's becosh they're a shilicashe—a shillycaysheou—" Cohen paused, and wiped his beard, "made out of rocks."

What could he possibly be saying? I had no idea; the best someone I asked could possibly think of was "Shillelagh", a word for a club that came from Irish. However, that really doesn't make much sense here.

1 Answer
1

The word Cohen is trying to say is "Silicate;" a common mineral in many forms of rock.

Common silicates include quartz (silicon dioxide) and granite (a combination of 3 different types of silicates: feldspar, quartz and mica). Most of Earth's crust is composed of silicates.

(He then tries to say "silicateous" - made of silicates - which is a step too far, and he gives up. Interestingly, even though "silicateous" is the adjectival form I'm familiar with, and I've read in scientific articles, according to the dictionary "siliceous" is the correct adjectival form. Even my spell-checker knows it.)